In vivo modulation of angiogenesis by beta 2 glycoprotein I

Beta 2 glycoprotein I (β2GPI) is the major auto antigen in the antiphospholipid syndrome but also interacts with fibrinolytic and angiogenic proteins. The aim of this study was to examine the angiogenic potential of β2GPI in vivo in β2GPI deficient mice utilizing angiogenic assays. β2GPI deficient mice show increased microvessel formation in comparison to β2GPI replete controls when injected with growth factor free-matrigel implants. However, microvessel formation in matrigel plugs of β2GPI deficient mice was less than in β2GPI replete mice when basic fibroblast growth factor (bFGF) was included in the matrigel. Hemoglobin content was higher in vascular endothelial growth factor (VEGF) containing-matrigel plugs in the β2GPI deficient mouse demonstrating that the lack of β2GPI led to increased extravasation by VEGF. Melanoma B16F10 tumour growth was enhanced in β2GPI deficient mice. Melanoma microvessel density was increased in β2GPI deficient mice but the proliferation rate of tumour cells (determined by Ki67 immunohistochemistry) was unaffected by the presence or absence of β2GPI. Subcutaneous delivery of native human β2GPI by the ALZET osmotic pump did not affect melanoma tumour growth in β2GPI deficient mice. We conclude that the in vivo unopposed action of β2GPI is anti-angiogenic however this function is modified in the presence of a strong angiogenic stimulus into stabilization of vessel formation. Although the presence of β2GPI attenuates vessel sprouting in certain tumours, no survival benefit is conferred to tumour bearing animals. This does not preclude the potential benefit of modified or fragments of β2GPI in anti-angiogenesis research.

Allergic sensitization is enhanced in early life through toll-like receptor 7 activation

BACKGROUND

Prospective cohort studies suggest that children hospitalized in early life with severe infections are significantly more likely to develop recurrent wheezing and asthma.

OBJECTIVE

Using an inhalational mouse model of allergic airways inflammation, we sought to determine the effect of viral and bacterial-associated molecular patterns on the magnitude of the allergic inflammatory response and whether this effect was age dependent.

METHODS

BALB/c mice were sensitized by intranasal administration of endotoxin(low) ovalbumin (OVA) in the absence or presence of viral single-stranded (ss)RNA, lipoteichoic acid or flagellin as neonates (within the first 24 h of life) or as weanlings (4 weeks of age). Mice were challenged four times with OVA at 6 weeks of age and end-points (bronchoalveolar lavage cytology, histology, antigen-specific T and B cell responses) determined at 7 weeks of age.

RESULTS

Inhalational sensitization (<24 h or 4 weeks of age) and challenge with OVA induced a mild allergic inflammatory response in the airways as indicated by increased numbers of eosinophils and mucus cells, elevated serum OVA-specific IgG1, and production of T helper 2 (Th2) cytokines. Mice sensitized to endotoxin(low) OVA at birth in the presence of ssRNA or lipoteichoic acid, but not flagellin, showed an increase in the numbers of airway and tissue eosinophils, mucus producing cells and antigen-specific production of IL-13 as compared with mice exposed only to endotoxin(low) OVA. By contrast, all three TLR ligands failed to increase the magnitude of OVA-induced allergic inflammation in mice sensitized as weanlings.

CONCLUSIONS

Recognition of distinct microbial-associated patterns in early life may preferentially promote the de novo differentiation of bystander, antigen-specific CD4(+) T cells toward a Th2 phenotype, and promote an asthma-like phenotype upon cognate antigen exposure in later life.

The roles of eotaxin and the STAT6 signalling pathway in eosinophil recruitment and host resistance to the nematodes Nippostrongylus brasiliensis and Heligmosomoides bakeri

Expulsion of adult Nippostrongylus brasiliensis worms from the small intestine is profoundly impaired in signal transducer and activator of transcription (STAT)6-deficient mice. IL-5 transgenic (Tg) mice with constitutive eosinophilia show profound early resistance in the skin and/or later pre-lung phase of primary infections with N. brasiliensis. This study was designed to assess the importance of the eosinophil chemokine eotaxin and the STAT6/interleukin (IL)-4/IL-13 signalling pathway in early resistance to N. brasiliensis. Eosinophil recruitment into the skin following injection of N. brasiliensis larvae was reduced in STAT6- or eotaxin-deficient/IL-5 Tg double mutant mice. While ablation of eotaxin did not impair resistance in the pre-lung phase of N. brasiliensis infections in IL-5 Tg mice, elimination of STAT6 caused a modest reduction in resistance in both primary and secondary infections on this genetic background. STAT6(-/-)-, IL-13(-/-)- and IL-4Ralpha(-/-)-deficient single mutant and IL-13(-/-)/IL-4Ralpha(-/-) double mutant mice were more susceptible than WT mice during the pre-lung phase of secondary N. brasiliensis infections. In contrast, primary or secondary resistance were unaffected at either the pre-lung or gut stages of infection in eotaxin(-/-) single mutant mice. STAT6(-/-) and eotaxin(-/-) mice with or without the IL-5 transgene, were no more susceptible than WT or IL-5 Tg mice to protracted primary infections with Heligmosomoides bakeri, a parasitic nematode that is restricted to the gut. Our data suggest that parasitic nematodes that transit through the skin and lungs en route to the gut may be susceptible to early (pre-lung) innate and adaptive immune mechanisms that are dependent on the STAT6/IL-4/IL-13 signalling pathway, and this may be important for the development of effective therapies and vaccines.

Mechanism of interleukin-25 (IL-17E)-induced pulmonary inflammation and airways hyper-reactivity

BACKGROUND

IL-25, a novel member of the IL-17 cytokine family, promotes CD4+ T-helper 2 lymphocyte-like (Th type-2) inflammatory responses in the lung. Although IL-25 up-regulates IL-13 in the lung, the contribution of this and other type 2 cytokine signalling pathways to the induction and persistence of airways hyper-reactivity (AHR) and allergic inflammation are unclear.

OBJECTIVE

To determine the downstream factors employed by IL-25 to induce Th type-2 pulmonary inflammation and AHR.

METHODS

IL-25 was delivered to the airways of BALB/c mice by intra-tracheal (i.t.) instillation and AHR and Th type-2 inflammatory responses were characterized in wild type (WT) and Th type-2-cytokine and -signalling pathway-deficient (-/-) mice.

RESULTS

IL-25 treatment resulted in AHR, eosinophilic inflammation, mucus hypersecretion and a progressive increase in the production of Th type-2 cytokines in the lungs. Levels of arginase-I (arg-I) and eotaxin were also elevated by IL-25 treatment. A significant reduction in AHR, and attenuation of mucus production was observed in IL-25-treated IL-13-/-, IL-4 receptor alpha (IL-4Ralpha-/-)- and signal-transducer-and-activator-of-transcription-factor-6 (STAT6-/-)-deficient mice. AHR was also inhibited in IL-4(-/-)- and IL-5/eotaxin(1)(-/-)- deficient mice treated with IL-25, however, mucus hypersecretion was not completely ablated. IL-25 promoted Th type-2 responses by directly acting on naïve T cells.

CONCLUSION

IL-25 potently (single dose) induces sustained AHR and acute pulmonary inflammation with eosinophilia. IL-25-induced AHR is dependent on the production of Th type-2 cytokines, and removal of IL-13 and its signal transduction pathway prevents IL-25-induced airways inflammation and AHR. IL-25 potently induces inflammatory cascades that may exacerbate allergic airways inflammation by promoting Th type-2 cytokine responses in conjunction with the up-regulation of factors (eotaxin and arg-I) that can amplify inflammation associated with allergic disorders. Dysregulation in IL-25 production may predispose to features of allergic airways disease.

Flightless I deficiency enhances wound repair by increasing cell migration and proliferation

Wound healing disorders are a therapeutic problem of increasing clinical importance involving substantial morbidity, mortality, and rising health costs. Our studies investigating flightless I (FliI), a highly conserved actin-remodelling protein, now reveal that FliI is an important regulator of wound repair whose manipulation may lead to enhanced wound outcomes. We demonstrate that FliI-deficient + /- mice are characterized by improved wound healing with increased epithelial migration and enhanced wound contraction. In contrast, FliI-overexpressing mice have significantly impaired wound healing with larger less contracted wounds and reduced cellular proliferation. We show that FliI is secreted in response to wounding and that topical application of antibodies raised against the leucine-rich repeat domain of the FliI protein (FliL) significantly improves wound repair. These studies reveal that FliI affects wound repair via mechanisms involving cell migration and proliferation and that FliI might represent an effective novel therapeutic factor to improve conditions in which wound healing is impaired.

Enhanced effect of dopaminergic stimulation on prepulse inhibition in mice deficient in the alpha subunit of G(z)

RATIONALE

G(z) is a member of the G(i) G protein family associated with dopamine D2-like receptors; however, its functions remain relatively unknown. The aim of the present study was to investigate prepulse inhibition (PPI) of acoustic startle, locomotor hyperactivity and dopamine D2 receptor binding in mice deficient in the alpha subunit of G(z).

METHODS

We used automated startle boxes to assess startle and PPI after treatment with saline, amphetamine, apomorphine or MK-801. We used photocell cages to quantitate locomotor activity after amphetamine treatment. Dopamine D2 receptor density was determined by autoradiography.

RESULTS

Startle responses and baseline PPI were not different between the Galpha(z) knockout mice and wild-type controls (average PPI 46+/-4 vs 49+/-3%, respectively). Amphetamine treatment caused a marked disruption of PPI in Galpha(z) knockouts (average PPI 22+/-2%), but less so in controls (average PPI 42+/-3%). Similar genotype-dependent responses were seen after apomorphine treatment (average PPI 23+/-3% vs 40+/-3%), but not after MK-801 treatment (average PPI 29+/-5 vs 33+/-2%). Amphetamine-induced locomotor hyperactivity was greater in Galpha(z) knockouts than in controls. There was no difference in the density of dopamine D2 receptors in nucleus accumbens.

CONCLUSIONS

Mice deficient in the alpha subunit of G(z) show enhanced sensitivity to the disruption of PPI and locomotor hyperactivity caused by dopaminergic stimulation. These results suggest a possible role for G(z) in neuropsychiatric illnesses with presumed dopaminergic hyperactivity, such as schizophrenia.

Deletion of guanine nucleotide binding protein alpha z subunit in mice induces a gene dose dependent tolerance to morphine

The mechanism underlying the development of tolerance to morphine is still incompletely understood. Morphine binds to opioid receptors, which in turn activates downstream second messenger cascades through heterotrimeric guanine nucleotide binding proteins (G proteins). In this paper, we show that G(z), a member of the inhibitory G protein family, plays an important role in mediating the analgesic and lethality effects of morphine after tolerance development. We blocked signaling through the G(z) second messenger cascade by genetic ablation of the alpha subunit of the G protein in mice. The Galpha(z) knockout mouse develops significantly increased tolerance to morphine, which depends on Galpha(z) gene dosage. Further experiments demonstrate that the enhanced morphine tolerance is not caused by pharmacokinetic and behavioural learning mechanisms. The results suggest that G(z) signaling pathways are involved in transducing the analgesic and lethality effects of morphine following chronic morphine treatment.

Interleukin-13 mediates airways hyperreactivity through the IL-4 receptor-alpha chain and STAT-6 independently of IL-5 and eotaxin

Interleukin (IL)-13 is a central mediator of the processes underlying the induction of airways hyperreactivity (AHR) in the allergic lung. However, the mechanisms by which IL-13 induces AHR and the associated role of inflammatory infiltrates as effector cells has not been fully elucidated. In this investigation, we show that intratracheal administration of IL-13 induces AHR in the presence and absence of inflammation. The initial AHR response (peak, 6 to 24 h; preinflammatory phase [PIP]) was dissociated from inflammation (eosinophilia) and mucus hypersecretion but was critically regulated by signaling through the IL-4 receptor alpha chain (IL-4Ralpha) and signal transducers and activators of transcription (STAT)-6. The second response (> 24 h, inflammatory phase [IP]) was characterized by an amplified AHR, eosinophil accumulation, and mucus hypersecretion. These features of the IP were not observed in IL-4Ralpha- or STAT-6-deficient mice. To determine the role of eosinophils in the induction of IP AHR and mucus hypersecretion, we administered IL-13 to IL-5-, eotaxin-, and IL-5/eotaxin- deficient mice. IL-13-mediated eosinophil accumulation was significantly attenuated (but not ablated) in IL-5-, eotaxin-, or IL-5/eotaxin-deficient mice. However, IL-13-induced AHR and mucus secretion occurred independently of IL-5 and/or eotaxin. These findings demonstrate that IL-13 can induce AHR independently of these eosinophil regulatory cytokines and mucus hypersecretion. Furthermore, IL-13-induced AHR, eosinophilia, and mucus production are critically dependent on the IL-4Ralpha chain and STAT-6.

IL-13 induces eosinophil recruitment into the lung by an IL-5- and eotaxin-dependent mechanism

BACKGROUND

IL-13 induces several characteristic features of asthma, including airway eosinophilia, airway hyperresponsiveness, and mucus overproduction; however, the mechanisms involved are largely unknown.

OBJECTIVE

We hypothesized that IL-13-induced inflammatory changes in the lung were dependent in part on IL-5 and eotaxin, two eosinophil-selective cytokines.

METHODS

Recombinant murine IL-13 was repeatedly administered to the lung by intranasal delivery until the characteristic features of asthma developed. To analyze the role of IL-5 and eotaxin, we subjected eotaxin gene-targeted, IL-5 gene-targeted, eotaxin/IL-5-double-deficient, IL-5 transgenic, and wild-type mice of the Balb/C background to the experimental regime.

RESULTS

The induction of IL-13-mediated airway eosinophilia was found to occur independently of eosinophilia in the blood or bone marrow, indicating that IL-13-induced airway inflammation is primarily mediated by local effects of IL-13 in the lung. Eosinophil recruitment into both the lung tissue and bronchoalveolar lavage fluid was markedly attenuated in IL-5-deficient mice in comparison with wild-type controls. Accordingly, IL-13 delivery to IL-5 transgenic mice resulted in a large increase in airway eosinophils in comparison with wild-type mice. Interestingly, IL-13-induced eosinophilia in the bronchoalveolar lavage fluid of eotaxin-deficient mice was not impaired; however, these same mice failed to mount a significant tissue eosinophilia in response to IL-13. Finally, IL-13-induced mucus production was not affected by the presence of IL-5 or eotaxin, suggesting that IL-13-induced mucus secretion is mechanistically dissociated from airway eosinophilia.

CONCLUSION

Selective components of the IL-13-induced asthma phenotype--airway eosinophilia but not mucus secretion--are differentially regulated by IL-5 and eotaxin. IL-5 is required for IL-13 to induce eosinophilia throughout the lung, whereas eotaxin regulates the distribution of airway eosinophils.

IL-13 induces airways hyperreactivity independently of the IL-4R alpha chain in the allergic lung

The potent spasmogenic properties of IL-13 have identified this molecule as a potential regulator of airways hyperreactivity (AHR) in asthma. Although IL-13 is thought to primarily signal through the IL-13Ralpha1-IL-4Ralpha complex, the cellular and molecular components employed by this cytokine to induce AHR in the allergic lung have not been identified. By transferring OVA-specific CD4(+) T cells that were wild type (IL-13(+/+) T cells) or deficient in IL-13 (IL-13(-/-) T cells) to nonsensitized mice that were then challenged with OVA aerosol, we show that T cell-derived IL-13 plays a key role in regulating AHR, mucus hypersecretion, eotaxin production, and eosinophilia in the allergic lung. Moreover, IL-13(+/+) T cells induce these features (except mucus production) of allergic disease independently of the IL-4Ralpha chain. By contrast, IL-13(+/+) T cells did not induce disease in STAT6-deficient mice. This shows that IL-13 employs a novel component of the IL-13 receptor signaling system that involves STAT6, independently of the IL-4Ralpha chain, to modulate pathogenesis. We show that this novel pathway for IL-13 signaling is dependent on T cell activation in the lung and is critically linked to downstream effector pathways regulated by eotaxin and STAT6.

Enhanced resistance in STAT6-deficient mice to infection with ectromelia virus

We inoculated BALB/c mice deficient in STAT6 (STAT6(-/-)) and their wild-type (wt) littermates (STAT6(+/+)) with the natural mouse pathogen, ectromelia virus (EV). STAT6(-/-) mice exhibited increased resistance to generalized infection with EV when compared with STAT6(+/+) mice. In the spleens and lymph nodes of STAT6(-/-) mice, T helper 1 (Th1) cytokines were induced at earlier time points and at higher levels postinfection when compared with those in STAT6(+/+) mice. Elevated levels of NO were evident in plasma and splenocyte cultures of EV-infected STAT6(-/-) mice in comparison with STAT6(+/+) mice. The induction of high levels of Th1 cytokines in the mutant mice correlated with a strong natural killer cell response. We demonstrate in genetically susceptible BALB/c mice that the STAT6 locus is critical for progression of EV infection. Furthermore, in the absence of this transcription factor, the immune system defaults toward a protective Th1-like response, conferring pronounced resistance to EV infection and disease progression.

Antiviral potential of chemokines

In the past few years, a large number of new chemokines (chemotactic cytokines) and chemokine receptors have been discovered. The growth in knowledge about these molecules has been achieved largely through advances in bioinformatics and the expansion of expression sequence tag (EST) databases. It is now clear that chemokines are crucial in controlling both the development and functioning of leukocytes and that their role is not restricted to cell attraction, as originally assumed. In particular, recent findings provide strong support for the idea that chemokines and their receptors are especially important in the control of viral infection and replication. Thus, specific chemokines are now known to enhance the cytotoxic activity of infected cells, thus inhibiting further virus replication. In addition, some chemokines orchestrate the recruitment of activated leukocytes to foci of infection to aid viral clearance. Viruses, in turn, have evolved various defences against chemokines. These range from the production of proteins that inhibit biological activity of the host chemokine to the hijacking of the chemokine system, whereby certain viruses utilize chemokine receptors for their entry. The latter viral defence can itself be blocked by chemokines. Altogether, these findings illustrate the central role of chemokines in many different phases of the immune response, particularly those aspects involving antiviral defence, a variety and versatility that was not fully appreciated even a few years ago.

Distinct spatial requirement for eosinophil-induced airways hyperreactivity

T helper (Th)-2-derived cytokines and their involvement in the recruitment and activation of inflammatory cells crucially orchestrate asthma pathogenesis. A notable cellular component of this allergy-induced inflammation is the eosinophil. However, whether the eosinophil is an obligatory mediator for enhancing airways hyperreactivity (AHR) to cholinergic stimuli, a watershed of the asthmatic lung, is somewhat controversial. In this investigation we have endeavoured to define the spatial requirements for IL-4 and IL-13, and the downstream effector molecules, IL-5 and the CC chemokine eotaxin, for the recruitment of eosinophils and the development of AHR in a murine model of allergic pulmonary disease. These studies are of particular importance considering clinical trials, with either the soluble IL-4Ralpha subunit or a humanized anti-IL-5 antibody, are being conducted. Interestingly, our studies show that depletion of both IL-4 and IL-13 is necessary to ablate pulmonary eosinophilia and AHR, and that this may be attributed to the role these cytokines play in regulating the expression of the eosinophil- activating molecules, IL-5 and eotaxin. While it is clear that depletion of IL-5 diminishes pulmonary eosinophilia, we demonstrate in BALB/c mice that a deficiency in both IL-5 and eotaxin is necessary to abolish both the trafficking of eosinophils to the lung and AHR. However, in contrast to the neutrophil-rich inflammation observed in mice deficient in both IL-4 and IL-13, inflammation per se in mice deficient in both IL-5 and eotaxin is significantly attenuated. This suggests that asthma immunotherapy may be better directed towards the eosinophil- activating molecules IL-5 and eotaxin, rather than towards pleiotrophic molecules such IL-4 and IL-13, which are additionally important in modulating alternative inflammatory responses.

Targeted disruption of the mouse Gz-alpha gene: a role for Gz in platelet function?

Gz is one of nine G proteins identified in platelets and its role in these cells is unknown. Our laboratory has generated a mouse deficient in the Gz-alpha gene in the hope of determining its in vivo function. Bleeding times from the tail tip of Gzalpha deficient mice was significantly longer than wild type mice. Platelet aggregation and ATP secretion did not differ between wild type and Gzalpha deficient mice. When mice were presented with a thromboembolism challenge no differences were observed in the survival or mortality of wild type or Gzalpha deficient mice, however a strain difference was observed. Ignoring the genetic background of a mutant mouse might lead to a misinterpretation of results and thus it is absolutely critical to take the genetic background into account when assessing any aspect of a mutant mouse.

A one-step quantitative reverse transcription polymerase chain reaction procedure

Our laboratory has developed a one-step quantitative reverse transcription polymerase chain reaction (RT-PCR) procedure in which the reverse transcriptase enzyme and Taq DNA polymerase are combined in the one tube and a single, non-interrupted, thermal cycling program is performed. In the past, RT-PCR has been carried out with two separate steps: (1) reverse transcription of RNA to generate a cDNA pool and (2) polymerase chain reaction amplification of the cDNA. The two-step method can affect the accuracy of the procedure as the total number of manipulations is greater, thereby allowing a greater chance for pipetting errors. Quantitation by our method is achieved in a single reaction by the use of a competitive internal standard that is identical in sequence to the target RNA except for a deletion of 107 base pairs and uses identical primers and cycling conditions. Using this method, we have been able to quantify the amount of message of a G protein (G(zalpha)), in small amounts of tissue, such as dorsal root ganglia, from embryonic as well as postnatal mice.

Elemental signals regulating eosinophil accumulation in the lung

In this review we identify the elemental signals that regulate eosinophil accumulation in the allergic lung. We show that there are two interwoven mechanisms for the accumulation of eosinophils in pulmonary tissues and that these mechanisms are linked to the development of airways hyperreactivity (AHR). Interleukin-(IL)-5 plays a critical role in the expansion of eosinophil pools in both the bone marrow and blood in response to allergen provocation of the airways. Secondly, IL-4 and IL-13 operate within the allergic lung to control the transmigration of eosinophils across the vascular bed into pulmonary tissues. This process exclusively promotes tissue accumulation of eosinophils. IL-13 and IL-4 probably act by activating eosinophil-specific adhesion pathways and by regulating the production of IL-5 and eotaxin in the lung compartment. IL-5 and eotaxin co-operate locally in pulmonary tissues to selectively and synergistically promote eosinophilia. Thus, IL-5 acts systemically to induce eosinophilia and within tissues to promote local chemotactic signals. Regulation of IL-5 and eotaxin levels within the lung by IL-4 and IL-13 allows Th2 cells to elegantly co-ordinate tissue and peripheral eosinophilia. Whilst the inhibition of either the IL-4/IL-13 or IL-5/eotaxin pathways resulted in the abolition of tissue eosinophils and AHR, only depletion of IL-5 and eotaxin concurrently results in marked attenuation of pulmonary inflammation. These data highlight the importance of targeting both IL-5 and CCR3 signalling systems for the resolution of inflammation and AHR associated with asthma.

Critical role for signal transducer and activator of transcription factor 6 in mediating intestinal muscle hypercontractility and worm expulsion in Trichinella spiralis-infected mice

Intestinal nematode infections in rats or mice are accompanied by intestinal muscle hyper contractility that may contribute to parasite expulsion from the gut. Previous studies demonstrated that both the expulsion of nematode parasites and the associated muscle hyper contractility are dependent on CD4(+) T helper cells. Nevertheless, the precise immunological mechanism underlying changes in intestinal muscle function remains to be determined. In this study, we investigated the role of interleukin 4 (IL-4) and signal transducer and activator of transcription factor 6 (STAT6) in the development of intestinal muscle hypercontractility and worm expulsion by infecting IL-4 and STAT6-deficient mice with Trichinella spiralis. Worm expulsion was almost normal in IL-4-deficient mice but substantially delayed in STAT6-deficient mice. Consistent with delayed worm expulsion, we also observed a marked attenuation of carbachol-induced muscle contraction in STAT6-deficient mice but only a moderate decrease in muscle hypercontractility in IL-4-deficient mice. In addition, we also observed severe impairment of T helper type 2 cytokine responses and intestinal mucosal mastocytosis in STAT6-deficient mice, although some degree of intestinal tissue eosinophilia was evident in these animals. These results are consistent with the hypothesis that STAT6-dependent changes in intestinal muscle function contribute to host protection in nematode infection.

Stat6 dependent goblet cell hyperplasia during intestinal nematode infection

To identify the role of signal transducer and activator of transcription factor 6 (Stat6) in the development of intestinal goblet cell hyperplasia during nematode infection, we compared the number of goblet cells in Stat6 deficient (Stat6 -/-) mice with that generated in wild-type (Stat6 +/+) mice in Trichinella spiralis infection. The number of goblet cells significantly increased with infection in wild-type mice. However, Stat6 -/- failed to generate infection-induced goblet cell hyperplasia and a significantly lower number of goblet cells was observed in Stat6 -/- mice on days 14 and 21 postinfection compared to Stat6 +/+ mice. In addition to suppressed goblet cell numbers, Stat6 -/- mice exhibited severe impairment in their ability to produce IL-4 and IL-13 and to expel the parasites from the gut. Our study clearly shows an essential role of Stat6 in intestinal goblet cell hyperplasia which accompanies this infection. We postulate that Th2 cytokines regulate the development of goblet cell hyperplasia in gut during nematode infection via Stat6 activation and that the increased number of goblet cells plays an important role in host protective immunity against the infection.

Uterine eosinophils and reproductive performance in interleukin 5-deficient mice

Interleukin 5 is expressed in type 2 T lymphocytes and has a key role in driving the differentiation, recruitment and activation of eosinophils. Mice with a null mutation in the interleukin 5 gene (IL-5 -/- mice) have altered type 2 immune responses and severely depleted eosinophil populations. In the present study, the effect of interleukin 5 deficiency on the abundant population of eosinophils present in the female reproductive tract was investigated, and the reproductive performance in C57Bl/6 IL-5 -/- mice was measured. Endometrial eosinophils, detected on the basis of their endogenous peroxidase activity, were reduced in number by four-sevenfold during the oestrous cycle and in early pregnancy in IL-5 -/- mice. Eosinophils present in the cervix and decidual tissues at the time of parturition were similarly diminished. The temporal fluctuations in eosinophil recruitment and localization within these tissues were otherwise unchanged, indicating that interleukin 5 is not a necessary chemotactic agent in the female reproductive tract. Oestrous cycles were moderately greater in duration in IL-5 -/- mice (mean +/- SD = 5.6 +/- 1.0 days in IL-5 -/- mice versus 5.0 +/- 0.8 days in IL-5 +/+ mice), owing to an extended period in oestrus (2.7 +/- 0.9 days per cycle in IL-5 -/- mice versus 1.8 +/- 0.7 in IL-5 +/+ mice). The interval between placing females with males and the finding of copulatory plugs was reduced significantly in interleukin 5-deficient mice. Implantation rates and subsequent fetal development were comparable in IL-5 -/- and IL-5 +/+ mice, irrespective of whether pregnancies were sired by syngeneic (C57Bl/6) or allogeneic (CBA or Balb/c) males, apart from a 10% increase in placental size and a 6.5% decrease in placental∶fetal ratio seen on day 17 in pregnancies sired by CBA males. Parturition and post-partum uterine repair were not compromised in interleukin 5-deficient mice, as judged by the length of gestation, and the outcomes of pregnancies initiated at post-partum oestrus. The birth weights and growth trajectories of pups were significantly influenced by interleukin 5 status, with small but significant increases in the weights of IL-5 -/- pups, particularly C57Bl/6 and CBA F(1) animals, remaining evident until adulthood. These data are consistent with the view that eosinophils have a role in endometrial tissue remodelling associated with the oestrous cycle, but indicate that the events of pregnancy and parturition proceed quite normally in the absence of maternal and fetal interleukin 5. However, strain-dependent effects of interleukin 5 deficiency on placental growth and function and subsequent weight gain in the newborn indicate that this cytokine may act through the maternal or fetal immune axis to exert subtle influences on reproductive outcome.

Uterine eosinophils and reproductive performance in interleukin 5-deficient mice

Interleukin 5 is expressed in type 2 T lymphocytes and has a key role in driving the differentiation, recruitment and activation of eosinophils. Mice with a null mutation in the interleukin 5 gene (IL-5 -/- mice) have altered type 2 immune responses and severely depleted eosinophil populations. In the present study, the effect of interleukin 5 deficiency on the abundant population of eosinophils present in the female reproductive tract was investigated, and the reproductive performance in C57Bl/6 IL-5 -/- mice was measured. Endometrial eosinophils, detected on the basis of their endogenous peroxidase activity, were reduced in number by four-sevenfold during the oestrous cycle and in early pregnancy in IL-5 -/- mice. Eosinophils present in the cervix and decidual tissues at the time of parturition were similarly diminished. The temporal fluctuations in eosinophil recruitment and localization within these tissues were otherwise unchanged, indicating that interleukin 5 is not a necessary chemotactic agent in the female reproductive tract. Oestrous cycles were moderately greater in duration in IL-5 -/- mice (mean +/- SD = 5.6 +/- 1.0 days in IL-5 -/- mice versus 5.0 +/- 0.8 days in IL-5 +/+ mice), owing to an extended period in oestrus (2.7 +/- 0.9 days per cycle in IL-5 -/- mice versus 1.8 +/- 0.7 in IL-5 +/+ mice). The interval between placing females with males and the finding of copulatory plugs was reduced significantly in interleukin 5-deficient mice. Implantation rates and subsequent fetal development were comparable in IL-5 -/- and IL-5 +/+ mice, irrespective of whether pregnancies were sired by syngeneic (C57Bl/6) or allogeneic (CBA or Balb/c) males, apart from a 10% increase in placental size and a 6.5% decrease in placental&ratio;fetal ratio seen on day 17 in pregnancies sired by CBA males. Parturition and post-partum uterine repair were not compromised in interleukin 5-deficient mice, as judged by the length of gestation, and the outcomes of pregnancies initiated at post-partum oestrus. The birth weights and growth trajectories of pups were significantly influenced by interleukin 5 status, with small but significant increases in the weights of IL-5 -/- pups, particularly C57Bl/6 and CBA F(1) animals, remaining evident until adulthood. These data are consistent with the view that eosinophils have a role in endometrial tissue remodelling associated with the oestrous cycle, but indicate that the events of pregnancy and parturition proceed quite normally in the absence of maternal and fetal interleukin 5. However, strain-dependent effects of interleukin 5 deficiency on placental growth and function and subsequent weight gain in the newborn indicate that this cytokine may act through the maternal or fetal immune axis to exert subtle influences on reproductive outcome.

Interleukin-5 deficient mice exhibit impaired host defence against challenge Trichinella spiralis infections

Enteric nematode infections are characterized by both peripheral and tissue eosinophilia. The cytokine interleukin (IL)-5 is considered a critical factor in the proliferation and recruitment of eosinophils, however, studies suggest it plays little role in host defence, at least during primary Trichinella spiralis infections. Less is known concerning its role in host defence or in the inflammatory response that develops against challenge infections with the same parasite. We examined these questions by infecting IL-5 deficient and wild-type mice, with T. spiralis parasites. Both strains expelled the primary infection by day 21. Forty days after the primary infection, we challenged the mice with a second T. spiralis infection and counted tissue eosinophils and worms in the intestine. While wild-type mice developed a large tissue eosinophilia, IL-5 deficient mice showed little increase in eosinophil numbers within the intestine. Throughout the challenge infection, significantly larger worm burdens were recovered from IL-5 deficient mice, and worm expulsion was also significantly slower (day 21) compared to wild-type mice (day 14). Thus, unlike in a primary infection, IL-5 is not only essential for the onset of intestinal eosinophilia, but also makes a significant contribution to enteric host defence during challenge T. spiralis infections.

The flightless I protein localizes to actin-based structures during embryonic development

The product of the flightless I gene is predicted to provide a link between molecules of an as yet unidentified signal transduction pathway and the actin cytoskeleton. Previous work has shown that weak and severe mutations of the flightless I locus in Drosophila melanogaster cause disruption in the indirect flight muscles and in embryonic cellularization events, respectively, indicative of a regulatory role for the flightless I protein in cytoskeletal rearrangements. A C-terminal domain within flightless I with significant homology to the gelsolin-like family of actin-binding proteins has been identified, but evidence of a direct interaction between endogenous flightless I and actin remains to be shown. In the present study, chick, mouse and Drosophila melanogaster embryos have been examined and the localization of flightless I investigated in relation to the actin cytoskeleton. It is shown that flightless I localization is coincident with actin-rich regions in parasympathetic neurons harvested from chicks, in mouse blastocysts and in structures associated with cellularization in Drosophila melanogaster.

Hypertolerance to morphine in G(z alpha)-deficient mice

Our laboratory has generated a mouse deficient in the alpha (alpha) subunit of the G protein, G(z), (G(z alpha)) gene and we have examined the involvement of G(z alpha) in spinal and supraspinal analgesia and tolerance mechanisms. Spinal analgesia was tested by the response times to heat or cold tail flick times in a water bath at 50 degrees C or -5 degrees C and supraspinal analgesia was tested by the times for paw licking and jumping from a plate at 52 degrees C or 0.5 degrees C. Tolerance to morphine was induced in wild type and G(z alpha)-deficient mice over a 5 day period and the behavioral tests were performed daily. The tail flick reaction times to both hot and cold stimuli did not differ between the wild type and G(z alpha)-deficient mice. Analysis of the reaction times from the hot and cold plate tests showed the G(z alpha)-deficient mice developed tolerance to morphine to a greater degree and at a faster rate than wild type mice. Opioid binding assays were performed on synaptic membranes prepared from naive and morphine tolerant wild type and G(z alpha)-deficient brains. No changes in the affinity of morphine for its receptor or in the density of mu and delta opioid receptors were found between the two groups of mice in the naive or morphine tolerant state. This indicates that the absence of G(z alpha) does not affect opioid receptor affinity or receptor up or down regulation. Our results suggest that the presence of G(z alpha) delays the development of morphine tolerance and represents a possible therapeutic target for improving the clinical use of morphine.

A role for IL-5 in the induction of cytotoxic T lymphocytes in vivo

IL-5 is generally regarded as a Th2 cytokine involved in eosinophil maturation and function and in B cell growth and antibody production, but without any well-established effects on T cells. Early reports suggested that IL-5 could stimulate the production of cytotoxic T lymphocytes (CTL) in vitro, but no evidence has been obtained to date for such a role in studies with IL-5-deficient (IL-5-/-) mice. Here we demonstrate that when oxidized mannan MUC1 fusion protein (M-FP) is used as an antigen in mice, IL-5 is required for the optimal generation of the CTL response. IL-5 was as effective as IL-2 for the induction of CTL from spleen cells in vitro and both CD4+ and CD8+ T cells from M-FP-immunized animals could be shown to secrete IL-5 in culture. In IL-5-/- mice, CTLp frequency was greatly diminished resulting in the inability to reject MUC1- tumors. Clearly, IL-5 is produced by functional T cells, especially the Tc1 type, after M-FP immunization and is required for an optimal CTL response to this antigen.

The effect of IL-5 and eotaxin expression in the lung on eosinophil trafficking and degranulation and the induction of bronchial hyperreactivity

The mechanisms regulating the selective migration and degranulation of eosinophils in the asthmatic lung and the subsequent development of airways hyperreactivity (AHR) have not been fully delineated. In this investigation, we have employed a novel transgene model to facilitate the dissection of the contributions of IL-5 and/or eotaxin to eosinophil function in the absence of complex tissue signals derived from the allergic lung. Gene transfer of IL-5 and/or eotaxin to the lungs of naive mice induced a pronounced and selective airways eosinophilia, but did not result in eosinophil degranulation or AHR. Airways eosinophilia occurred independently of the induction of a blood eosinophilia, but was markedly augmented by the coexpression of both cytokines and/or by the transient mobilization of eosinophils from the bone marrow by the administration of i.v. IL-5. However, for eosinophil degranulation and AHR to occur, the inhalation of Ag was required in association with IL-5 and eotaxin expression. Investigations in IL-5-deficient mice linked eosinophilia, and not solely IL-5 and eotaxin, with the induction of AHR. Furthermore, eosinophil degranulation and AHR were dependent on CD4+ T cells. Importantly, this investigation shows that IL-5 regulates eosinophilia within the lung as well as in the circulation and also amplifies eotaxin-induced chemotaxis in the airway compartment. Moreover, the interplay between these cytokines, CD4+ T cells, and factors generated by Ag inhalation provides fundamental signals for eosinophil degranulation and the induction of AHR.

Eosinophilia is attenuated in experimental colitis induced in IL-5 deficient mice

Tissue eosinophilia is a feature of idiopathic inflammatory bowel disease and other forms of colonic inflammation but it is not clear whether the role of eosinophils in the disease process is to contribute to tissue damage. Interleukin 5 (IL-5) stimulates production and activation of eosinophils in vitro and enhances immunoglobulin A (IgA) production. As very little is known about the function of IL-5 in the colon, the aim of this study was to assess its role in colonic inflammation. IL-5 deficient mice were studied using the dextran sulphate sodium (DSS)-induced colitis model and the results compared to a congenic IL-5+/+ strain. The absence of IL-5 resulted in reduction of tissue eosinophilia (P < 0.0001) but was not reflected in differences in the severity of the disease (P > 0.5) or in the extent of tissue damage in this model of colitis. Numbers of immunoglobulin-containing cells in IL-5 deficient mice were similar to those in the IL-5+ mice. We conclude that the main role of IL-5 in DSS-induced colonic inflammation is to attract a population of eosinophils which do not appear to contribute significantly to the initiation or development of tissue damage in this model of colitis.

IL-5 contributes to worm expulsion and muscle hypercontractility in a primary T. spiralis infection

Enteric nematode infections lead to increased interleukin (IL)-5 expression, eosinophilic inflammation, and intestinal smooth muscle hypercontractility. Although eosinophils release inflammatory mediators that cause smooth muscle contraction, the role of IL-5 and eosinophils in enteric smooth muscle hypercontractility is unclear. IL-5-deficient mice and their wild-type controls were infected with the nematode Trichinella spiralis. Intestinal parasites and eosinophils were counted, and jejunal longitudinal muscle contractility was assessed. During infection, IL-5 gene expression increased significantly in wild-type mice and was accompanied by significant intestinal eosinophilia in wild-type but not IL-5-deficient mice. Although both strains developed increased muscle contractility during infection, contraction was significantly less in the IL-5-deficient mice at days 16 and 21 postinfection. In addition, parasite expulsion was transiently delayed at day 16 in IL-5-deficient mice. Thus, in the nematode-infected mouse, IL-5 appears essential for intestinal eosinophilia and contributes to, but is not essential for, the development of muscle hypercontractility. IL-5 also appears to play a minor role in expelling a primary T. spiralis infection from the gut.

Loss of antiviral cytotoxic T-lymphocyte activity during high-level antigen stimulation

High levels of antigenic stimulation can result in deactivation of CD8+ T cells through a variety of mechanisms, including insufficient T-cell help. In the present study, an adoptive transfer system was established in which ovalbumin (OVA)-specific CD8+ T cells were transferred to irradiated mice infected with a recombinant vaccinia virus encoding OVA (VV-OVA). Prolonged activation of OVA-specific CD8+ T cells resulted in a proliferative block in these cells, although cytotoxic function was maintained. Unlike naive and recently activated OVA-specific T cells, these nonproliferative cytotoxic CD8+ T cells did not have antiviral activity following further transfer to mice infected with VV-OVA. Provision of interleukin-2 (IL-2) at the site of virus infection using a recombinant virus encoding antigen and IL-2, as well as the addition of helper T cells, had no effect on the generation of these dysfunctional T cells. Thus, there was no evidence that lack of T-cell help was responsible for CD8+ T-cell deactivation in this model.

Stress induces neurogenesis in non-neuronal cell cultures of adult olfactory epithelium

Among the basal cells of the olfactory epithelium is a stem cell which divides and whose progeny differentiate into new sensory neurons throughout adult life. Olfactory neurogenesis is highly regulated, for example it is stimulated by epithelial damage. Previous reports implicate several growth factors in progenitor cell proliferation and neuronal differentiation in vitro but these studies differ in growth conditions and age of donors making it difficult to determine precisely the roles of neurogenic stimuli and their sites of action. The aims of the present study were to develop purified basal cell cultures from adult olfactory epithelium and to stimulate neurogenesis in defined growth conditions in order to elucidate the cellular mechanisms by which neurogenesis is stimulated after epithelial damage. We show here that differentiated olfactory sensory neurons arise after biochemical or mechanical stress of rat and mouse olfactory epithelial cell cultures in the absence of growth factors, complex media (e.g., serum, conditioned media, pituitary and hypothalamic extracts), or other cells (e.g., explants, feeder layers of glia, or other non-epithelial cells). Prior to the stress, these cultures contained basal cells and supporting cells but not neurons. After the stress, some cells differentiated into bipolar neurons expressing a number of neuronal proteins including olfactory marker protein. Bromodeoxyuridine experiments show that the differentiated neurons arose from recently divided cells which did not divide again before differentiating. We conclude that stress disrupts cell surface contacts to induce the immediate neuronal precursors to undergo final differentiation into olfactory sensory neurons. This may be a mechanism for enhanced neurogenesis after epithelial damage.

Regulation of primary Strongyloides ratti infections in mice: a role for interleukin-5

C57BL/6 mice genetically deficient in interleukin-5 (IL-5-/-) and normal C57BL/6 (IL-5+/+) mice were infected with larvae of a homogonic strain of the nematode Strongyloides ratti. In primary infections both male and female IL-5-/- mice released two to four times more eggs and larvae than IL-5+/+ mice. IL-5-/- mice harboured about 60% more intestinal worms, which were more fecund, than IL-5+/+ mice. The duration of the infection was similar in normal and IL-5-deficient mice. Both IL-5-/- and IL-5+/+ mice resisted a secondary infection. IL5-/- mice lost more weight during the infection than normal mice and took longer to regain their initial weight after expelling the worms. The number of eosinophils increased in the bone marrow, peritoneal cavity and small intestine of IL-5+/+ mice, but not IL-5-/- mice, following infection. No significant differences between infected IL-5+/+ and IL-5-/- mice in mast cells or other leucocytes were observed in the peritoneal cavity. Thus, IL-5 functions to protect the host in a primary infection of S. ratti by limiting the number and fecundity of worms establishing in the small intestine. This protection is correlated with elevated blood and tissue eosinophilia which occurs in normal mice but not in IL-5-/- mice.

Circulating, but not local lung, IL-5 is required for the development of antigen-induced airways eosinophilia

IL-5 is induced locally in the lung and systemically in the circulation during allergic airways eosinophilic inflammation both in humans and experimental animals. However, the precise role of local and systemic IL-5 in the development of allergic airways eosinophilia remains to be elucidated. In our current study, we demonstrate that compared with their IL-5(+/+) counterparts, IL-5(-/-) mice lacked an IL-5 response both in the lung and peripheral blood, yet they released similar amounts of IL-4, eotaxin, and MIP-1alpha in the lung after ovalbumin (OVA) sensitization and challenge. At cellular levels, these mice failed to develop peripheral blood and airways eosinophilia while the responses of lymphocytes, neutrophils, and macrophages remained similar to those in IL-5(+/+) mice. To dissect the relative role of local and systemic IL-5 in this model, we constructed a gene transfer vector expressing murine IL-5. Intramuscular IL-5 gene transfer to OVA-sensitized IL-5(-/-) mice led to raised levels of IL-5 compartmentalized to the circulation and completely reconstituted airways eosinophilia upon OVA challenge, which was associated with reconstitution of eosinophilia in the bone marrow and peripheral blood. Significant airways eosinophilia was observed for at least 7 d in these mice. In contrast, intranasal IL-5 gene transfer, when rendered to give rise to a significant but compartmentalized level of transgene protein IL-5 in the lung, was unable to reconstitute airways eosinophilia in OVA-sensitized IL-5(-/-) mice upon OVA-challenge, which was associated with a lack of eosinophilic responses in bone marrow and peripheral blood. Our findings thus provide unequivocal evidence that circulating but not local lung IL-5 is critically required for the development of allergic airways eosinophilia. These findings also provide the rationale for developing strategies to target circulating IL-5 and/or its receptors in bone marrow to effectively control asthmatic airways eosinophilia.

Overexpression of fra-2 in transgenic mice perturbs normal eye development

The major components of transcription factor AP-1 (Activator Protein 1) are encoded by the two families of genes related to the proto-oncogenes c-fos and c-jun. The fos-related antigen-2 (fra-2) gene is the most recently described member of the Fos family. To determine the oncogenic potential of fra-2, transgenic mice were generated which over-express fra-2 in a number of tissues. No tumours were evident in any transgenic mice up to 18 months of age, although eye development was severely disrupted in these animals. Corneal abnormalities could be observed histologically as early as embryonic day 15.5 and eyelid fusion failed to occur. Adult eyes were characterized by generalized anterior segment dysgenesis similar to that previously reported in transgenic mice over-expressing transforming growth factor alpha (TGF alpha), and occasionally microphthalmia. Expression of fra-2 was shown to increase following TGF alpha treatment of cells in vitro, suggesting that AP-1 complexes containing Fra-2 contribute to TGF alpha signalling events.

The role of interleukin-5 (IL-5) in vivo: studies with IL-5 deficient mice

Eosinophil recruitment is a characteristic feature of a number of pathological conditions and was the topic of the recent International Symposium on allergic inflammation, asthma, parasitic and infectious diseases (Rio de Janeiro, June 3-5, 1996). Since interleukin-5 (IL-5) is believed to regulate the growth, differentiation and activation of eosinophils (Coffman et al. 1989, Sanderson 1992), the role of eosinophils and IL-5 are closely linked. Although IL-5 specifically regulates eosinophilia in vivo and this is its most well established activity, it is becoming clear that IL-5 also has other biological effects. The recent derivation of an IL-5 deficient mouse (Kopf et al. 1996), provides a model for exploring not only the role of IL-5 and eosinophils but also other novel activities of IL-5. Of note is that although the IL-5 deficient mice cannot elicit a pronounced eosinophilia in response to inflammatory stimulation following aeroallergen challenge or parasite infection they still produce basal levels of eosinophils that appear to be morphologically and functionally normal. However, the basal levels of eosinophils appear insufficient for normal host defense as IL-5 deficiency has now been shown to compromise defense against several helminth infections. In addition, IL-5 deficient mice appear to have functional deficiencies in B-1 B lymphocytes and in IgA production.

Interleukin-4 and interleukin-5 as targets for the inhibition of eosinophilic inflammation and allergic airways hyperreactivity

Clinical and experimental investigations suggest that allergen-specific CD4+ T-cells, IgE and the cytokines IL-4 and IL-5 play central roles in initiating and sustaining an asthmatic response by regulating the recruitment and/or activation of airways mast cells and eosinophils. IL-5 plays a unique role in eosinophil development and activation and has been strongly implicated in the aetiology of asthma. The present paper summarizes our recent investigations on the role of these cytokines using cytokine knockout mice and a mouse aeroallergen model. Investigations in IL-5-/-mice indicate that this cytokine is critical for regulating aeroallergen-induced eosinophilia, the onset of lung damage and airways hyperreactivity during allergic airways inflammation. While IL-4 and allergen-specific IgE play important roles in the regulation of allergic disease, recent investigations in IL-4-/- mice suggest that allergic airways inflammation can occur via pathways which operate independently of these molecules. Activation of these IL-4 independent pathways are also intimately associated with CD4+ T-cells, IL-5 signal transduction and eosinophilic inflammation. Such IL-5 regulated pathways may also play a substantive role in the aetiology of asthma. Thus, evidence is now emerging that allergic airways disease is regulated by humoral and cell mediated processes. The central role of IL-5 in both components of allergic disease highlights the requirements for highly specific therapeutic agents which inhibit the production or action of this cytokine.

A novel T cell-regulated mechanism modulating allergen-induced airways hyperreactivity in BALB/c mice independently of IL-4 and IL-5

The immunoregulatory functions of IL-4 and IL-5 have identified these cytokines as primary targets for the resolution of airways inflammation and bronchial hyperreactivity in asthma. However, the individual contribution of each of these cytokines and of IL-5-regulated eosinophilia to the induction of airways hyperreactivity in mouse models of asthma remains highly controversial. In this investigation, we have used IL-4- and IL-5-deficient mice of the same genetic background in combination with inhibitory mAbs to these cytokines to identify unequivocally the contribution of these factors to the induction of airways hyperreactivity. Sensitization and aeroallergen challenge of wild-type mice with OVA induced pathological changes to the respiratory epithelium, airways eosinophilia, and hyperreactivity to beta-methacholine. Inhibition of the actions of IL-4 and/or IL-5 did not abolish airways hyperreactivity, and in the case of IL-4-deficient mice pretreated with anti-IL-5 mAb, airways hyperreactivity persisted in the absence of pronounced airways inflammation. Airways hyperreactivity was abolished only by anti-CD4+ mAb treatment. However, aeroallergen challenge of IL-5-/- mice showed that morphologic changes to the airways were critically linked to IL-5 and eosinophilia. This investigation demonstrates the existence in BALB/c mice of a novel CD4+ T cell pathway for modulating airways hyperreactivity. These findings may provide an explanation for the dissociation of airways eosinophilia from the development of airways hyperreactivity observed in some cases of asthma and in animal models of this disease.

Intestinal IgA plasma cells of the B1 lineage are IL-5 dependent

Two lineages of B cells, designated B1 and B2 cells, have been identified based upon their origins, anatomical distribution, cell surface markers, antibody repertoire and self-replenishing potential. B1 cells are maintained by self-renewal of cells resident in the peritoneal cavity (PerC) and they utilize a limited repertoire of germline V-region genes, mostly directed against ubiquitous bacterial antigens such as phosphoryl choline (PC). B2 cells are replenished from bone marrow precursors and use a larger repertoire of immunoglobulin V-region genes. Whereas most immunoglobulin A (IgA) plasma cells in the intestine derive from B2 lineage precursors in the Peyer's patch, a subpopulation of Per C-derived B1 cells populate the intestinal lamina propria where they mature into IgA plasma cells. In previous in vivo studies we have shown that whereas IgA+ B2 cells are interleukin (IL)-6 dependent, B1 cells are IL-6 independent. In view of the in vitro evidence that IL-5 is also involved in IgA expression, in the studies reported here we have used IL-5-deficient mice to evaluate the role of IL-5 in vivo in IgA expression in the gut. The results demonstrate that although total IgA cell numbers are only marginally depressed in IL-5-deficient mice, there is a marked selective depletion of IgA+ cells of the B1 lineage in the gut and a corresponding depression in the capacity of these mice to mount an intestinal response to a B1 antigen (PC) but not to a B2 antigen (oralbumin; OVA), reflecting intact B2-derived IgA cell function but a defect in the B1 cell contribution to IgA responses in IL-5 deficient mice. Collectively these data demonstrate differential cytokine regulation of subsets of IgA+ cells in the gut in that IgA+ cells of the B2 lineage are IL-6 dependent but IL-5 independent, but B1-derived IgA+ cells are IL-5 dependent and IL-6 independent.

Developmental expression of messenger RNA levels of the alpha subunit of the GTP-binding protein, Gz, in the mouse nervous system

There has been recent evidence that Gz may play a role in the transmission of the neurotrophic signal from nerve terminals to the cell bodies [Johanson, S.O., Crouch, M.F., Hendry, I.A., Signal transduction from membrane to nucleus: the special case for neurons, Neurochem. Res. 21 (1996) 779-785]. We examined the developmental expression of the alpha subunit of Gz (Gzalpha) in the peripheral and central nervous systems of the mouse. Our laboratory has developed a quantitative reverse transcription-polymerase chain reaction (RT-PCR) for Gzalpha which makes use of a fragment of the PCR product shortened by 107 base pairs creating a standard which mimics the original RNA. Serial dilutions of the mouse RNA with a constant concentration of mimic RNA were made and the point where equal amounts of product are formed allows accurate measurement of Gzalpha mRNA in the tissue. We have demonstrated that in the developing mouse superior cervical ganglion (SCG), dorsal root ganglion (DRG) and trigeminal ganglion the expression of Gzalpha mRNA is highest perinatally. From 3 weeks of age, in all tissues with the exception of the SCG, Gzalpha mRNA levels fall to lower levels in the adult animal. The developmental pattern of expression of Gzalpha in both the cerebellum and the brain differs from the peripheral nervous system. In the cerebellum, Gzalpha mRNA expression is highest around birth and in the brain it is highest around third postnatal week and then the levels decline as adulthood is approached. These results suggest that the highest level of Gzalpha mRNA is expressed at the time when target tissue innervation is occurring. This further strengthens the hypothesis that Gzalpha is important in the transfer of information from target tissues to the innervating nerve cells.

Use of polymerase chain reaction to diagnose a natural outbreak of mouse hepatitis virus infection in nude mice

The enormous cost of eliminating mouse hepatitis virus (MHV) from a mouse colony demands that a confirmed etiologic diagnosis be made to justify the necessary remedial action. We describe an outbreak of MHV in nude mice in which histopathologic findings provided a presumptive diagnosis, but results of serologic testing of affected nude mice and immunocompetent sentinels were negative. Results of transmission electron microscopy of liver specimens from affected mice were equivocal. Confirmation of the etiopathogenesis was eventually provided by reverse transcriptase-polymerase chain reaction (RT-PCR), using primers with nested sequences directed to two separate but highly conserved regions of the MHV genome. This procedure detected MHV in the liver of an affected nude mouse and in a sentinel, although in the latter a positive result was obtained only because of the increased sensitivity of nested primers used in a second round of amplification. Virus was not detected in cell lines that had been injected into the mice, and the source of the outbreak was not found. These results indicate the applicability of RT-PCR for detecting MHV in a field situation while also illustrating that conventional, complementary techniques still have an essential role in reaching a diagnosis. It is recommended that specimens should be taken for histologic examination and serologic testing, as well as for molecular studies when MHV infection is suspected.

Interleukin-5-producing CD4+ T cells play a pivotal role in aeroallergen-induced eosinophilia, bronchial hyperreactivity, and lung damage in mice

Although activated CD4+ T cells have been implicated in the pathogenesis of asthma, the direct contribution of this leukocyte to the induction of aeroallergen-induced bronchial hyperreactivity and lung damage is unknown. In the present investigation, we have used a model of allergic airways inflammation, which displays certain phenotypic characteristics of late-phase asthmatic responses, together with interleukin-5-deficient (IL-5-/- ) mice and donor antigen-specific CD4+ TH2-type cells to obtain unequivocal evidence for a role of this T lymphocyte in the pathophysiology of allergic airways inflammation. Antigen-primed CD4+ T cells and CD4- cells (CD4+-depleted population) were purified from the spleens of ovalbumin (OVA)-sensitized wild-type mice and adoptively transferred to OVA-sensitized and nonsensitized IL-5-/- mice. In vitro stimulation of the purified cell populations with OVA resulted in the secretion of IL-4 and IL-5, but not interferon-gamma, from the CD4+ T cells, indicating that they were of the TH2 type. In contrast, interferon-gamma, but not IL-4 and IL-5, was produced by the CD4- T cells. The CD4+ TH2-type cells (but not the CD4 cells) reconstituted aeroallergen (OVA)-induced blood and airways eosinophilia, lung damage, and airways hyperreactivity to 1-methacholine in IL-5-/- mice. The reconstitution did not require prior sensitization of the mice, but it did not occur if they were aerosolized with saline instead of OVA. The circulating levels of OVA-specific -IgE and -IgG1 were not significantly altered by the adoptive transfer of either cell population. These investigations establish that IL-5-secreting CD4+ TH2-type cells play a pivotal role in generating blood and airways eosinophilia and in the subsequent development of bronchial hyperreactivity and lung damage that occurs in response to aeroallergens.

The isolation and cloning of chromosomal DNA specific for a clonal population of Staphylococcus aureus by subtractive hybridisation

Subtractive hybridisation was used to screen for and identify conserved DNA sequences associated with clinical, clonal populations of Staphylococcus aureus. DNA from S. aureus strain ISP8 (a clinical isolate) was digested with TaqI and hybridised with randomly fragmented pooled DNA from 10 non-clinical (community) isolates of S. aureus. The mixture of DNA fragments was then ligated to AccI-digested and dephosphorylated pTZ19U. One recombinant plasmid (pWASA) was identified as containing specific DNA from strain ISP8; DNA sequencing revealed a 40-bp TaqI DNA fragment (WASA). PCR amplification and hybridisation analysis, with pWASA as a probe, showed that 84% of clinical isolates from a clonal line present in hospitals in major eastern Australian cities carried sequences homologous to WASA, compared with only 10% of community isolates. The isolates that hybridised were closely related by RFLP analysis to strain ISP8. The plasmid pWASA was used to identify, isolate and clone a 3.5-kb DraI fragment (DSA) from strain ISP8 total DNA. Sequence analysis of the DSA fragment identified two open reading frames (ORFs) of 2475 and 576 bp, respectively; the larger ORF1 contained a series of six tandem repeats, each consisting of 384 nucleotides. The nucleotide sequence of the repeats was 96% identical, and no significant sequence homologies to previously described protein sequences were identified. However, tandem repeats of amino acids are structural motifs characteristic of a number of gram-positive surface proteins, and are thought to play a role in generating genetic and phenotypic diversity in these and other bacteria.

Enhancement of the specific mucosal IgA response in vivo by interleukin-5 expressed by an attenuated strain of Salmonella serotype Dublin

It has been shown that cytokines have potential as therapeutic adjuvants in vaccination. Interleukin-5 (IL-5) is a cytokine that regulates antibody production, in particular enhancing IgA production by activated mucosal B cells. This study examined the expression of a cloned cytokine gene encoding murine IL-5 (mIL-5) by an attenuated aroA strain (SL5631) of Salmonella serotype Dublin. The resulting strain, SL5631(pTRXFUS-mIL-5), expressed mIL-5 as a fusion with thioredoxin as demonstrated by immunological and biological assays. When strain SL5631(pTRXFUS-mIL-5) was used as a live vaccine in BALB/c mice, it colonised and multiplied at higher levels in spleens and livers than the strain carrying the empty plasmid. A reduction in invasiveness of SL5631(pTRXFUS-mIL-5) was observed in in-vitro invasion assays. Enhanced IgA response against salmonella LPS in mucosal secretions and enhanced IgA and IgG responses were detected by ELISA and ELISPOT methods in sera of mice immunised with the strain expressing mIL-5. Results with IL-5-deficient mice showed that the enhanced IgA response was due to Salmonella-expressed mIL-5 rather than endogenous mIL-5.

Eosinophilia, parasite burden and lung damage in Toxocara canis infection in C57Bl/6 mice genetically deficient in IL-5

C57Bl/6 mice genetically deficient in interleukin (IL)-5 (IL-5-/-) and mice with the normal IL-5 gene (IL-5+/+) were infected with embryonated eggs of Toxocara canis. IL-5+/+ mice developed a marked eosinophilia in their peripheral bloods and bone marrows after infection. In contrast, the number of eosinophils at these sites actually decreased during the acute phase of infection in IL-5-/- mice. A smaller number of eosinophils infiltrated the lung, liver, heart and skeletal muscle of infected IL-5-/- mice than those of infected IL-5+/+ mice. Eosinophils were not produced in cultures of bone marrow cells from either IL-5+/+ or IL-5-/- mice which were stimulated with excretory secretory antigen of T. canis larvae. The capacity of cells from the bone marrow to differentiate into eosinophils when stimulated in vitro with recombinant murine IL-5 was the same whether the cells were from IL-5+/+ or IL-5-/- mice. Taken together, these results show that an IL-5-like molecule is not produced by the T. canis larvae and that IL-5 produced by host cells is solely responsible for the eosinophilia in mice infected with this nematode. The number and location of T. canis larvae were not altered in the absence of IL-5. In contrast, lung damage in infected IL-5-/- mice was less extensive than that in infected IL-5+/+ mice, although structures resembling Charcot-Leyden crystals were seen in the lungs of both IL-5+/+ and IL-5-/- mice. These results suggest that eosinophils play a role in the pathology in mice infected with T. canis.

Eosinophils are not required for the rejection of neovascularized fetal pig proislet xenografts in mice

The rejection of neovascularized pig proislet (islet precursor) xenografts in mice is a CD4 T cell-dependent process involving invasion of the graft site mainly by host CD4 T cells and eosinophils. We previously identified CD4 T cell-dependent enhancement of intragraft IL-3, IL-4, and IL-5 mRNA expression during acute xeno-rejection in CBA/H recipient mice. In the present study we investigated the role of each cytokine and the involvement of eosinophils in the rejection of pig proislet xenografts using cytokine gene knockout mice (IL-4 -/- and IL-5 -/-) and the treatment of transplant recipients with anti-IL-3 mAb. In IL-4 -/- mice, IL-5 -/- recipient animals, and anti-IL-3 mAb-treated CBA/H mice, eosinophil accumulation at the transplant site was inhibited or ablated, but the kinetics of xenograft rejection was unaltered. Prolonged xenograft survival was only achieved in anti-CD4 mAb-treated mice and consistently correlated with the absence of intragraft IL-3, IL-4, and IL-5 mRNA enhancement. Together these findings indicate that neither IL-3, nor IL-4, nor IL-5 individually plays an obligatory role in the rejection process. The cytokine mRNA profile correlating with the lack of eosinophil recruitment was variable; the data suggest that IL-4 regulates eosinophil involvement in the xeno-rejection reaction indirectly via effects on IL-5 and IL-3 transcript expression. There is also suggestive evidence that IL-5 may influence IL-3 and IL-4 mRNA expression via feedback inhibition. Eosinophils, therefore, do not play an essential role in the rejection of neovascularized pig proislet xenografts in mice.

Relationship between interleukin-5 and eotaxin in regulating blood and tissue eosinophilia in mice

The mechanism of cooperation between IL-5 and eotaxin for the selective accumulation of eosinophils at sites of allergic inflammation is unknown. In this investigation we have used IL-5 deficient mice to define the relationship between this cytokine and eotaxin in the regulation of blood eosinophilia and eosinophil homing and tissue accumulation. Both IL-5 and eotaxin could independently induce a rapid and pronounced blood eosinophilia in wild type mice when administered systemically. In contrast, only eotaxin induced a pronounced blood eosinophilia in IL-5 deficient mice. The eosinophilic response induced by intravenous eotaxin in wild type mice did not correlate with a significant reduction in the level of bone marrow eosinophils, whereas intravenous IL-5 resulted in depletion of this store. These results suggest the existence of two mechanisms by which eosinophils can be rapidly mobilized in response to intravenous eosinophil chemoattractants; first, mobilization of an IL-5 dependent bone marrow pool, and second, an eotaxin-induced sequestration of eosinophils from tissues into the blood. Subcutaneous injection of eotaxin induced a local tissue eosinophilia in wild type mice but not in IL-5 deficient mice. Furthermore, tissue eosinophilia in wild type mice, but not in IL-5 deficient mice, was enhanced by adoptive transfer of eosinophils or the administration of intravenous IL-5. However, pretreatment of IL-5 deficient mice with intraperitoneal IL-5 for 72 h restored eosinophil homing and tissue accumulation in response to subcutaneous eotaxin. We propose that eotaxin secreted from inflamed tissue may play an important role in initiating both blood and tissue eosinophilia in the early phases of allergic inflammation. Furthermore, IL-5 is not only essential for mobilizing eosinophils from the bone marrow during allergic inflammation, but also plays a critical role in regulating eosinophil homing and migration into tissues in response to eotaxin and possibly other specific chemotactic stimuli.

Eosinophils are not required for the rejection of neovascularized fetal pig proislet xenografts in mice

The rejection of neovascularized pig proislet (islet precursor) xenografts in mice is a CD4 T cell-dependent process involving invasion of the graft site mainly by host CD4 T cells and eosinophils. We previously identified CD4 T cell-dependent enhancement of intragraft IL-3, IL-4, and IL-5 mRNA expression during acute xeno-rejection in CBA/H recipient mice. In the present study we investigated the role of each cytokine and the involvement of eosinophils in the rejection of pig proislet xenografts using cytokine gene knockout mice (IL-4 -/- and IL-5 -/-) and the treatment of transplant recipients with anti-IL-3 mAb. In IL-4 -/- mice, IL-5 -/- recipient animals, and anti-IL-3 mAb-treated CBA/H mice, eosinophil accumulation at the transplant site was inhibited or ablated, but the kinetics of xenograft rejection was unaltered. Prolonged xenograft survival was only achieved in anti-CD4 mAb-treated mice and consistently correlated with the absence of intragraft IL-3, IL-4, and IL-5 mRNA enhancement. Together these findings indicate that neither IL-3, nor IL-4, nor IL-5 individually plays an obligatory role in the rejection process. The cytokine mRNA profile correlating with the lack of eosinophil recruitment was variable; the data suggest that IL-4 regulates eosinophil involvement in the xeno-rejection reaction indirectly via effects on IL-5 and IL-3 transcript expression. There is also suggestive evidence that IL-5 may influence IL-3 and IL-4 mRNA expression via feedback inhibition. Eosinophils, therefore, do not play an essential role in the rejection of neovascularized pig proislet xenografts in mice.

IL-5-deficient mice have a developmental defect in CD5+ B-1 cells and lack eosinophilia but have normal antibody and cytotoxic T cell responses

Mice deficient in interleukin-5 (IL-5-/- mice) were generated by gene targeting in embryonal stem cells. Contrary to previous studies, no obligatory role for IL-5 was demonstrated in the regulation of conventional B (B-2) cells, in normal T cell-dependent antibody responses or in cytotoxic T cell development. However, CD5+ B cells (B-1 cells) in the peritoneal cavity were reduced by 50%-80% in 2-week-old IL-5-/- mice, returning to normal by 6-8 weeks of age. The IL-5-/- mice did not develop blood and tissue eosinophilia when infected with the helminth Mesocestoides corti, but basal levels of eosinophils with normal morphology were produced in the absence of IL-5. IL-5 deficiency did not affect the worm burden of infected mice, indicating that increased eosinophils do not play a significant role in the host defence in this parasite model.

Interleukin 5 deficiency abolishes eosinophilia, airways hyperreactivity, and lung damage in a mouse asthma model

Airways inflammation is thought to play a central role in the pathogenesis of asthma. However, the precise role that individual inflammatory cells and mediators play in the development of airways hyperreactivity and the morphological changes of the lung during allergic pulmonary inflammation is unknown. In this investigation we have used a mouse model of allergic pulmonary inflammation and interleukin (IL) 5-deficient mice to establish the essential role of this cytokine and eosinophils in the initiation of aeroallergen-induced lung damage and the development of airways hyperreactivity. Sensitization and aerosol challenge of mice with ovalbumin results in airways eosinophilia and extensive lung damage analogous to that seen in asthma. Aeroallergen-challenged mice also display airways hyperreactivity to beta-methacholine. In IL-5-deficient mice, the eosinophilia, lung damage, and airways hyperreactivity normally resulting from aeroallergen challenge were abolished. Reconstitution of IL-5 production with recombinant vaccinia viruses engineered to express this factor completely restored aeroallergen-induced eosinophilia and airways dysfunction. These results indicate that IL-5 and eosinophils are central mediators in the pathogenesis of allergic lung disease.

Exclusion of defects in the skeletal muscle specific regions of the DHPR alpha 1 subunit as frequent causes of malignant hyperthermia

The molecular defect predisposing to the majority of malignant hyperthermia (MH) cases is unknown, although various point mutations in the ryanodine receptor gene (RYR1) have been associated with susceptibility in a small proportion of cases. We report here that one of these, the Arg163Cys substitution, does not cosegregate with MH susceptibility. Comparison of cDNA sequences encoding the skeletal muscle specific components of the dihydropyridine receptor alpha 1 subunit between MH susceptible (MHS) and MH non-susceptible (MHN) patients was made in subjects without the reported MH linked RYR1 mutations. There were no differences within the sequence encoding the II-III loop or the IS3/IS3-IS4 segment, excluding defects in these functional segments of the alpha 1 subunit as frequent causes of MH.

The role of interleukin-6 in mucosal IgA antibody responses in vivo

In mice with targeted disruption of the gene that encodes interleukin-6 (IL-6), greatly reduced numbers of immunoglobulin A (IgA)-producing cells were observed at mucosae and grossly deficient local antibody responses were recorded after mucosal challenge with either ovalbumin or vaccinia virus. The IgA response in the lungs was completely restored after intranasal infection with recombinant vaccinia viruses engineered to express IL-6. These findings demonstrate a critical role for IL-6 in vivo in the development of local IgA antibody responses and illustrate the effectiveness of vector-directed cytokine gene therapy.